If you do need to merge content from multiple projects into one, there is one way to do it in FMOD Studio: Simply open both projects at once, copy from one, and paste in the other. There are a few limits to this, but if you’re using imported Designer projects, none of them will apply to you; I mention them here only for other interested users: First, if your project uses event reference sound modules, you will have to copy the referenced and referencing events at the same time. Also, snapshots cannot be usefully copied and pasted between projects at this time.

That said, you should never need to merge projects made in Studio – because we’ve made it unnecessary. In FMOD Designer, there were two reasons to create multiple projects: It was almost impossible for multiple users to work on a project at once, and loading the entirety of a large project could take up more resources than some users had to spare. In FMOD Studio, we’ve solved those problems: Revision control integration makes it possible for multiple users to work on a single project without treading on each others’ toes, and “lazy loading” of only the parts of a project you’re working on means that larger projects only use a smidgeon more resources than smaller ones. There’s simply no longer any need to create multiple projects for a single game.

@MarkKnight Incidentally, we're more likely to notice follow-up questions if you post them as new questions instead of comments and answers on exiting ones; We only get notified of new posts under certain specific circumstances, so comments and answers can easily slip past us.

FYI, the reason I want to merge projects is that I am creating audio for various 1 vehicle simulators. There is a generic set of sounds which would be used for all simulators, whereas each simulator would have its own unique vehicle audio.

So, simply keeping one “misc audio” project up to date, and individual ‘vehicle’ projects makes the most sense to me.